A shift in the Bax/Bcl-2 balance may activate caspase-3 and modulate apoptosis in experimental glomerulonephritis

BACKGROUND: Although apoptosis has been linked to the renal cell deletion and ensuing renal fibrosis, its regulating mechanisms remain obscure. Of the known regulators of apoptosis, the best characterized is the Bax to Bcl-2 ratio. However, its importance in controlling apoptosis in glomerulonephritis is unclear. Here, using the nephrotoxic nephritis (NTN) model, we evaluated Bax/Bcl-2 in relation to changes in the apoptosis co-ordination enzyme, caspase-3. METHODS: Kidneys were harvested at days 7, 15, 30 and 45 post-injection of anti-glomerular basement membrane antibody into Wistar Kyoto rats. These were analyzed for apoptosis (in situ end labeling of fragmented DNA, light and electron microscopy), Bax/Bcl-2 protein (Western blotting), mRNA (Northern blotting) and distribution (immunohistochemistry), as well as caspase-3 activity (substrate cleavage assay), inflammation (ED1 staining), proliferation (proliferating cell nuclear antigen staining) and fibrosis (Masson's Trichrome staining). RESULTS: Bax mRNA was significantly increased while that of Bcl-2 was decreased throughout the time course (+265% and -62% by day 45). Increased Bax and decreased Bcl-2 protein were noted, significantly so on day 7 (+177% and -21%) and day 45 (+363% and -17%). Bax protein was observed in dilated and atrophic tubules, sclerotic glomeruli and inflamed interstitium, while Bcl-2 was only visible in atrophic tubules. The ratios of Bax to Bcl-2 mRNA and protein were significantly increased at all time points. These correlated (P < 0.05) with up-regulated caspase-3 activity (r = 0.742 and 0.531), apoptosis (r = 0.712 and 0.540), proliferation (r = 0.611, mRNA only), inflammation (ED1+, r = 0.474 and 0.419) and fibrosis (r = 0.474 and 0.729). CONCLUSIONS: Our findings suggest that the changes in the ratio of Bax to Bcl-2 may contribute to the caspase-3 activation and the modulation of renal apoptosis associated with renal inflammation, tubular atrophy and renal fibrosis in experimental glomerulonephritis.     

Progesterone differentially regulates pro- and anti-apoptotic gene expression in cerebral cortex following traumatic brain injury in rats

Although the administration of progesterone has been shown to be neuroprotective in experimental models of traumatic brain injury (TBI), the mechanisms for this beneficial effect are still poorly understood. The present study examined the effects of progesterone on mRNA and protein levels of the Bcl-2 apoptosis regulatory genes, bax, bad, bcl-2, and bcl-x(L), in cerebral cortex after TBI. Male Sprague-Dawley rats were subjected to either sham surgery or lateral fluid percussion brain injury of moderate severity (2.4-2.6 atm). Within 1 h post-surgery, progesterone (4 mg/kg) or vehicle (corn oil) administration was initiated for 1-7 days postoperatively. Our results indicate that bax and bad mRNA levels and Bax and Bad protein expression in the ipsilateral, injured cerebral cortex were significantly elevated post-TBI, while mRNA levels of bcl-2 and bcl-x(L) or Bcl-2 and Bcl-x(L) protein expression were not changed. Under the sham-treated condition, progesterone significantly increased mRNA levels of the anti-apoptotic gene, bcl-2, but down-regulated pro-apoptotic gene expression (bax and bad) in cerebral cortex. After TBI, progesterone treatment reduced bax and bad mRNA levels in the ipsilateral cerebral cortex of TBI rats, and decreased Bax and Bad protein levels. In addition, bcl-2 and bcl-x(L) mRNA levels, as well as Bcl-2 and Bcl-x(L) protein expression, were increased by progesterone in TBI injured cortex. These data indicate that one of the neuroprotective mechanisms of progesterone may be related to its differential regulation of apoptotic signals.     

Adenovirus-Mediated bcl-2 Gene Transfer Inhibits Renal Ischemia/Reperfusion Induced Tubular Oxidative Stress and Apoptosis

Ischemia/reperfusion induces oxidative injury to proximal and distal renal tubular cells. We hypothesize that Bcl-2 protein augmentation with adenovirus vector mediated bcl-2 (Adv-bcl-2) gene transfer may improve ischemia/reperfusion induced renal proximal and distal tubular apoptosis through the mitochondrial control of Bax and cytochrome C translocation. Twenty-four hours of Adv-bcl-2 transfection to proximal and distal tubular cells in vitro upregulated Bcl-2/Bax ratio and inhibited hypoxia/reoxygenation induced cytochrome C translocation, O(2) (-) production and tubular apoptosis. Intra-renal arterial Adv-bcl-2 administration with renal venous clamping augmented Bcl-2 protein of rat kidney in vivo in a time-dependent manner. The maximal Bcl-2 protein expression appeared at 7 days after Adv-bcl-2 administration and the primary location of Bcl-2 augmentation was in proximal and distal tubules, but not in glomeruli. With a real-time monitoring O(2) (-) production and apoptosis analysis of rat kidneys, ischemia/reperfusion increased renal O(2) (-) level, potentiated proapoptotic mechanisms, including decrease in Bcl-2/Bax ratio, increases in caspase 3 expression and poly-(ADP-ribose)-polymerase fragments and subsequent proximal and distal tubular apoptosis. However, Adv-bcl-2 administration significantly enhanced Bcl-2/Bax ratio, decreased ischemia/reperfusion induced O(2) (-) amount, inhibited proximal and distal tubular apoptosis and improved renal function. Our results suggest that Adv-bcl-2 gene transfer significantly reduces ischemia/reperfusion induced oxidative injury in the kidney.     

Cellular apoptosis and proliferation in experimental renal fibrosis

Background: The progression of chronic renal failure (CRF) is associated with the progressive deletion of renal cells along with the fibrosis of the kidney. We have studied the role of programmed cell death (apoptosis) in the progression of experimental CRF and renal scarring. Methods: The sub-total (5/6th) nephrectomy (SNx) model of CRF was studied in adult male Wistar rats, with renal tissue collected from experimental and control animals on days 7, 15, 30, 60, 90, and 120 post SNx (n-6 per group). These were examined for morphological signs of apoptosis by light and electron microscopy. Further, we stained the nuclear chromatin by the acridine orange fluorescent method and detected signs of DNA cleavage by endonucleases via the principal of TUNEL staining (ApopTag™). Rates of cellular proliferation were measured simultaneously by immunohistochemical staining for the proliferating cell nuclear antigen (PCNA). In addition, cell division was monitored by counting of morphologically mitotic motifs detectable by light microscopy. Results: Progressive renal insufficiency associated with glomerulosclerosis and tubulointerstitial fibrosis took place in the majority of SNx rats. In these animals, we noted a marked and progressive increase in the number of apoptotic glomerular, tubular as well as interstitial cells. The most significant apoptotic changes were seen in the tubules of remnant kidneys peaking at day 120 post-SNx. At this stage, the increase in apoptosis compared to controls was 10.33±2.67 (M±SEM) fold for glomerular cells (P⩽0.006), 26.20±4.56 fold for tubular cells (P<0.0001) and 4.66±0.81 fold for interstitial cells (P⩽0.01). Parallel changes in the number of PSNA positive renal cells were observed. Maximal PCNA staining was seen at day 120 when the increase with respect to controls was 14.00±4.93 fold (P⩽0.05) for glomerular cells, 60.01±12.20 fold (P⩽0.05) for tubular cells and 28.59±4.45 fold ((P⩽0.05) for interstitial cells. As expected the number of cells undergoing division and detectable by conventional light microscopy was lower at any time point to those expressing PCNA. We also observed a close correlation between the severity of tubular atrophy and tubulointerstitial fibrosis with the rate of tubular apoptosis (r=0.970, R²=0.941, P⩽0.001). Conclusions: We have shown a time-dependent increase in apoptosis and PCNA antigen positive staining in the sub-total nephrectomy model of chronic renal failure correlating with the progression of renal fibrosis. PCNA staining did not match analysis for mitosis and was considered to overestimate the number or proliferating cells in the tissue. With this reservation in mind and taking into account the relative time-frames in vivo of apoptosis and proliferation; apoptosis potentially outweighs proliferation by a factor of 2-8-fold, when examined over the same time period. Consequently, even small changes in the finite numbers of apoptotic cells become highly significant. Our results have shown the definite role of apoptosis within progression of renal damage and highlighted how it may contribute to the progression of tubular atrophy and play a role in the pathogenesis of tubulo-interstitial scarring.     

Chronic ureteral obstruction in the rat suppresses renal tubular Bcl-2 and stimulates apoptosis

Unilateral ureteral obstruction (UUO) results in widespread tubular apoptosis in obstructed kidneys of both adults and neonates. The oncoprotein bcl-2 inhibits many forms of apoptosis, whereas the related protein bax promotes apoptosis. To evaluate the interaction of bcl-2, bax, and apoptosis in the renal response to UUO, adult and neonatal rats were subjected to UUO or sham operation, and kidneys were harvested 14 days later. Apoptotic cells were identified by the Tunel technique, and the distribution of bcl-2 and bax was determined by immunochemistry. In both adults and neonates, tubular and interstitial apoptosis was present in the obstructed kidney, but not in intact kidneys. In both adults and neonates, there was diffuse tubular bcl-2 and bax staining of sham-operated and intact kidneys. While bcl-2 was increased in scattered nonapoptotic tubules of the obstructed kidney, there was minimal staining of dilated apoptotic tubules. These results are consistent with the premise that bcl-2 normally suppresses renal tubular apoptosis. The distribution of bax staining in tubules of the obstructed kidney overlapped that of bcl-2. We conclude that chronic UUO inhibits bcl-2 expression in selected tubules of the obstructed kidney which contributes to activation of apoptosis and progressive renal damage in either neonatal or adult kidneys. Dysregulation of apoptosis may be a response to renal injury similar to that underlying the development of cystic kidney disease or renal dysplasia.     

Expression of apoptosis-related proteins bcl-2 and bax along with transforming growth factor (TGF-beta1) in the kidney of patients with glomerulonephritides

BACKGROUND: Apoptosis, a gene-directed form of cell death, has been involved in the resolution of renal injury but also in the development of scarring. Bcl-2 and bax are proteins related to apoptotic process that either provides a survival advantage to rapidly proliferating cells (bcl-2) or promote cell death by apoptosis (bax). Various cytokines and growth factors are involved in this process. This study investigates the expression of bcl-2 and bax and the presence of apoptotic bodies in relation to the TGF-beta1 expression at the time of diagnosis in the renal biopsies of patients with glomerulonephritis (GN). METHODS: Fifty patients with various types of GN and ten controls were included in the study. Bcl-2, bax and Transforming Growth Factor (TGF-beta1) positive cells were detected in kidney biopsies by immunohistochemistry, while apoptotic cells were detected by in situ end labeling of fragmented DNA (ISEL). Morphometric analysis was used for quantitation of immunostaining. RESULTS: The intensity of bcl-2, bax and TGF-beta1 immunostaining in the renal tissue of patients with GN was significantly more to the observed in the control biopsies. Bcl-2 and bax were expressed within the epithelial cells of proximal, distal and collecting tubules and in the renal interstitium. Bax and bcl-2 proteins were also identified within the glomeruli in a few patients but their distribution was not related to the type of GN. TGF-beta1 was expressed in the cytoplasm of tubular epithelial cells and to a lesser extent in the renal interstitium and glomeruli. A positive correlation of TGF-beta1 with the extent of bax immunostaining (r=0.498, p<0.05) and an inverse correlation with that of bcl-2 (r= -0.490, p<0.05) were identified. Apoptotic bodies were identified only in the renal tissue of patients with GN and were mainly localized among tubular epithelial and interstitial cells. CONCLUSION: The intensity of bcl-2 and bax proteins expression and the presence of apoptotic bodies in the renal tissue of patients with GN suggest that apoptotic process is ongoing during the evolution of renal disease. The correlation of TGF-beta1 expression with that of apoptosis-related proteins might represent an implication of this growth factor with apoptotic process in the human diseased kidney.     

多囊卵巢综合征中卵巢初级小卵泡bcl-2、bax的表达

目的 :探讨凋亡调节蛋白 bcl-2及 bax在多囊卵巢综合征 ( PCOS)患者的卵泡选择、发育的作用。方法 :1 8例 PCOS患者及 1 3名正常人 2 40个小卵泡按直径分为 4个组 ,采用免疫组织化学方法及 Konton Ibas灰度值的定量测定 ,用 SPSS软件统计 ,定量分析凋亡调节蛋白 bcl-2及 bax在 PCOS各级初级小卵泡中的表达。结果 :PCOS组各级窦前卵泡组间 bax蛋白表达有显著差异 ,随着卵泡直径的增加 bax表达明显增多 ,但直径 >1 2 0 μm的卵泡 bax表达减少 ,bcl-2 / bax灰度比值显著变小。 bcl-2蛋白表达相对稳定 :PCOS组直径在 60～ 1 2 0μm的卵泡 bcl-2表达显著高于正常对照组 ( P<0 .0 5 )。结论 :正常人及 PCOS卵巢组织各级窦前卵泡和窦卵泡均表达 bcl-2及 bax,随着卵泡的增大 ,bcl-2的表达增加 ,当卵泡直径 >1 2 0 μm时 ,细胞凋亡减弱 ,卵泡的增长加速。PCOS患者卵巢中各级窦前卵泡和窦卵泡凋亡蛋白 bcl-2及 bax的表达是正常的。     

Apoptosis in prostate cancer: Bax correlation with stage

BACKGROUND: Dysregulation of apoptosis may contribute to the process of prostate tumorigenesis by reducing the rate of cell death. Bcl-2 and bax are important molecules involved in the regulation of apoptosis. The aim of the present study is to examine apoptosis and related regulatory molecular markers in a group of Iranian patients with prostate cancer. METHODS: Paraffin-embedded tissues from 50 patients of prostate carcinoma were examined for the expression of bcl-2 antiapoptotic and bax proapoptotic markers and also proliferation marker, Ki-67, by immunohistochemistry. Detection of apoptotic cells was performed using TUNEL method. Correlation between apoptotic index, proliferation index and bcl-2 and bax expression with stage, pathological grade and Gleason score was determined. RESULTS: Apoptosis was detected in 12% of prostate cancers. No correlation was observed between apoptosis and differentiation status of carcinoma. Bcl-2 expression was detected in 21 of samples. A significant correlation between bcl-2 expression and Ki-67 staining index (r = 0.349, P = 0.012) was observed. High bax protein expression was shown in our study. We found a significant correlation between bax expression and stage of carcinoma (r = 0.388, P = 0.031), but not with the apoptosis index, suggesting the presence of a non-functional bax protein or the role of other proapoptotic molecules. CONCLUSION: The patients in the present study showed a different pattern of apoptosis positivity compared to other reports. Bax expression may be a useful marker for prognosis of prostate cancer.     

The effect of rhubarb extract on experimental renal fibrosis

In order to explore the therapeutic potential of traditionalChinese medicinal herbs on the progression of experimental chronicrenal failure (CRF), we have studied the effect of orally administeredrhubarb extract on the course of CRF in rats submitted to subtotalnephrectomy (SNx). Adult male Wistar rats were submitted toeither a SNx (n=18) or a sham operation (n= 10). Thirty daysafter SNx, nine SNx and five sham operated rats were given aqueousrhubarb roots extract (150 mg/day) in drinking water. The ratswere followed up for 120 days. Rhubarb treatment had no effecton the systemic hypertension observed in SNx rats. Rhubarb-treatedSNx rats had significantly less proteinuria 90 days (172±63mg/24 h) and 120 days (228±92 mg/24 h) after SNx whencompared to untreated SNx controls (day 90, 246 ± 80mg/24 h; day 120, 335±113mg/24 h, P<0.05). Renal functionwas comparable in rhubarb-treated and untreated SNx rats. However,at sacrifice the severity of glomerulosclerosis was significantlyreduced in SNx rats treated with rhubarb (2.03±0.44;SNx controls, 2.58±0.53, P<0.05). The difference intubulointerstitial scarring between the two groups did not reachsignificance. Our results suggest that rhubarb extract reducesproteinuria and the severity of glomeruloscierosis in rats withremnant kidneys.     

凋亡相关基因bcl-2和bax在胆管癌组织中表达的意义

目的　探讨细胞凋亡抑制基因ｂｃｌ－ ２ 和凋亡促进基因ｂａｘ 在胆管癌组织中的表达。方法　应用免疫组化方法对２０ 例胆管癌（ＣＨＣ）和７例先天性胆总管囊肿（ＣＣＣ）组织中ｂｃｌ－ ２和ｂａｘ 蛋白进行检测。结果　２０例ＣＨＣ中有１例ｂｃｌ－ ２ 蛋白表达阳性（５％ ）,７例ＣＣＣ中ｂｃｌ－ ２均表达阴性。２０例ＣＨＣ中有１１ 例ｂａｘ 蛋白表达阳性（５５％ ）,７例ＣＣＣ中仅１ 例表达阳性（１４．２９％ ）,两组间差异有显著意义（Ｐ＜ ０．０１）。结论　ｂｃｌ－ ２ 和ｂａｘ 蛋白的改变在胆管癌发生发展过程中不起重要作用。     

IL-6影响骨髓基质细胞凋亡机理的初步探讨

目的通过观察IL-6对体外培养骨髓基质细胞凋亡的影响，探讨骨髓基质细胞凋亡的机理。方法取1月龄SD大鼠的骨髓基质细胞进行体外培养，通过透射电子显微镜观察、bax、bcl-2蛋白免疫组化染色、流式细胞仪检测凋亡细胞周期变化及线粒体跨膜电位改变、RT—PCR法检测凋亡细胞bax、bcl-2 mRNA表达等指标进行观察。结果IL-6组细胞G1期、凋亡率和线粒体膜电位改变均非常显著高于对照组；随着诱导时间的延长，Bcl-2 mRNA表达呈逐渐下降趋势，BaxmRNA表达呈逐渐升高趋势。Bcl-2／Bax：随着诱导时间的延长呈下降趋势。结论IL-6使大量细胞停留在G1期，阻滞细胞进入S期，使DNA合成受阻；IL-6促进凋亡的作用是通过1促进bax从胞浆中移至线粒体膜上而使bax在与bcl-2形成的异二聚体中占据优势来促进线粒体上的PT孔道开放，使内膜离子通道改变，线粒体内膜电位下降或丧失，导致Cyto c等蛋白的释放来调节细胞凋亡。     

Proapoptotic Bax is hyperexpressed in isolated human islets compared with antiapoptotic Bcl-2

BACKGROUND: Apoptosis is a well-documented pathway for islet cell death. One potential mechanism is overexpression of death-promoting Bax compared with antiapoptotic Bcl-2 in islets. METHODS: We isolated islets from 10 human pancreata and measured the expression of Bax mRNA and Bcl-2 mRNA by real-time quantitative polymerase chain reaction; islet and pancreas expression of Bax, Bcl-2, activated caspase-3, and cleaved poly (ADP-ribose) polymerase were also assessed by immunohistochemistry. Islet cell apoptosis was evaluated by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) assay and by flow cytometry. RESULTS: The mean (+/-SE) level of Bax mRNA was 336+/-79 copies per nanogram of total RNA, and the level of Bcl-2 mRNA was 36+/-10 (P=0.001). A positive correlation existed between islet expression of Bax mRNA and Bcl-2 mRNA (P=0.001). The islet Bax to Bcl-2 ratio was 10.8+/-1.3 and 1.71+/-0.3 for the spleens (P=0.0001). Bax mRNA (P=0.04), but not Bcl-2 mRNA, was expressed at a higher level in islets compared with spleens. Human islets contained large numbers of cells expressing Bax protein, whereas only infrequent islet cells expressed Bcl-2 protein, activated caspase-3, and poly (ADP-ribose) polymerase. The apoptotic index was 5% by TUNEL assay, and the percentage of apoptotic islet cells was 9.7+/-2.5% by flow cytometry. Sections of human pancreas before islet isolation showed islet staining for Bax but not Bcl-2. CONCLUSIONS: Our finding that isolated human islets express Bax at a higher level compared with Bcl-2 suggests a molecular mechanism for islet cell death by apoptosis. We hypothesize that reducing islet expression of Bax, or regulating its activation, will help preserve islet cell mass after islet transplantation.     

姜黄素抑制肾癌ACHN细胞增殖及促凋亡的实验研究

目的观察姜黄素对人肾癌ACHN细胞株增殖及细胞凋亡的影响,探讨姜黄素诱导ACHN细胞株凋亡的作用机制。方法不同浓度姜黄素作用人肾癌ACHN细胞24 h后,应用MTT比色法检测姜黄素对人肾癌ACHN细胞的增殖抑制率;流式细胞术检测姜黄素诱导细胞的凋亡率;RT-PCR检测姜黄素对ACHN细胞Bcl-2、Bax、NF-κBP65 mRNA表达的影响;Western blot方法检测其对细胞Bcl-2、Bax、NF-κBP65I、κB蛋白表达的影响。结果姜黄素对人肾癌ACHN细胞有明显的抑制作用,可引起细胞凋亡,并且存在剂量和时间依赖;不同浓度姜黄素作用细胞24 h后,Bcl-2、NF-κBP65 mRNA水平下降,Bax mRNA水平升高(P0.05),Bcl-2、NF-κBP65蛋白表达量下降,BaxI、κB蛋白表达量升高(P0.05)。结论姜黄素通过上调IκB,下调NF-κB活性,调控凋亡基因Bcl-2/Bax的表达,抑制人肾癌ACHN细胞的增殖,诱导人肾癌ACHN细胞的凋亡。     

Myofibroblast phenotypes expression in experimental renal scarring

Background. Myofibroblasts have been implicated in the pathogenesis of wound healing and tissue fibrosis. A role has also been put forward for these cells in the development of experimental and clinical renal scarring. Subjects and methods. We examined the expression of myofibroblast phenotypes by immunohistochemistry, relying on an avidin-biotin-peroxidase method, during the course of renal scarring in rats submitted to subtotal (5/6) nephrectomy (SNx). We also attempted to identify changes in immunoreactive transforming growth factor-{beta} (TGF-{beta}) and collagen (III and IV) within remnant kidneys in order to determine their association with the expression of the myofibroblasts. Results. In normal sham-operated rats, &agr;-smooth muscle actin (&agr;-SMA) was confined to the media of renal arteries and arterioles. In contrast, in rats with renal ablation we observed the early (day 7) appearance of myofibroblasts expressing &agr;-SMA (A) in the interstitium of remnant kidneys particularly around vessels. Interstitial cells expressing &agr;-SMA increased with time as tubulointerstitial fibrosis progressed. By day 30 some interstitial cells also expressed vimentin (V). Various interstitial myofibroblast phenotypes (A, V, VA) were expressed during the course of experimental renal scarring. Interstitial myofibroblasts appeared to be associated with TGF-{beta} as these cells' cytoplasm stained for both this growth factor and &agr;-SMA. Interstitial fibrosis was also associated with increased interstitial expression of both collage III and IV. Some atrophic tubular cells showed positive immunostaining for vimentin during the late stages of renal scarring (days 90-150). In the glomeruli, a segmental expression of &agr;-SMA was noted from day 21 after SNx onward. Normal glomerulal endothelial cells appeared to express vimentin while epithelial cells expressed both vimentin and desmin (D). The glomerular immunostain for vimentin increased with time but decreased as glomerulosclerosis progressed. In contrast, glomerula desmin and &agr;-SMA immunostain continued to rise with progressive glomerulosclerosis. This was associated with the appearance of type III collagen within scarred glomeruli. Both vimentin and desmin appeared within the walls of the renal arterioles and increased with time from day 7 and 15, respectively. Vimentin was also expressed in the peritubular capillaries of remnant kidneys. By contrast, &agr;-SMA, normally present in the media of arterioles, decreased as arteriolar sclerosis progressed. These changes cannot be exclusively attributed to systemic hypertension as they were absent in a group of age-matched, sham-operated, spontaneously hypertensive rats. Discussion: Myofibroblasts may play a role in the pathogenesis of glomerulosclerosis, tubulointerstitial fibrosis and vascular sclerosis. Further, the aquisition of new myofibroblastic phenotypes by glomerular and tubular cells may contribute to renal fibrosis.     

Increased expression of the pro-apoptotic ATP-sensitive P2X7 receptor in experimental and human glomerulonephritis.

BACKGROUND: The involvement of IL-1beta and other pro-inflammatory cytokines in most forms of glomerulonephritis is now well established. The P2X(7) receptor, an ATP-sensitive P2X receptor, functions not only as a non-selective cation channel, but it is also involved in the rapid processing and release of IL-1beta, apoptosis and necrotic cell death. Therefore, we wanted to investigate if expression of this receptor is altered in the glomeruli of rodent models of glomerulonephritis. METHODS: P2X(7) receptor protein expression was investigated using immunohistochemistry, and apoptosis was assessed using the TUNEL assay and caspase-3 immunostaining. Real-time PCR with gene-specific primers was used to detect P2X(7), IL-1beta, p53, bax and bcl-2 mRNA expression. RESULTS: Although the levels of the P2X(7) receptor protein in mouse kidney are normally very low, or undetectable, we detected an increase in glomerular expression of this receptor and an increase in glomerular apoptotic cells in a mouse model of accelerated nephrotoxic nephritis. We also observed increased glomerular and tubular expression of the P2X(7) receptor protein in renal biopsy tissue of patients with autoimmune-related glomerulonephritis. Furthermore, P2X(7) receptor mRNA increased in the kidneys of a rat model of proliferative glomerulonephritis and this coincided with the onset of proteinuria. We also observed increased mRNA expression of Il-1beta and the pro-apoptotic markers p53 and bax, but not of anti-apoptotic bcl-2. CONCLUSION: Although there is an association between expression of the pro-inflammatory and pro-apoptotic P2X(7) receptor and glomerulonephritis in these rodent models, and in at least one form of human glomerulonephritis, the underlying relationship and its functional significance remain to be explored.